_GH4145

GH4145 alloy is mainly a nickel-based superalloy with γ"[Ni3(Al, Ti, Nb)] phase aging strengthening. It has good corrosion resistance and oxidation resistance below 980℃, and high strength below 800℃. It has good relaxation resistance below 540°C, as well as good formability and welding performance. The alloy is mainly used to manufacture plane springs and coil springs that require high strength and resistance to relaxation, which work under 800°C for aero engines. It can also be used to manufacture gas turbine blades and other parts. Available varieties include plates, strips, bars, forgings, ring parts, wires and pipes.

Chinese name GH4145

Type alloy

Material designation GH4145 (GH145)
Melting temperature range 1395～1425℃

Introduction to Alloys

Material designation

GH4145（GH145）

Similar grades

Inconel X-750 (USA), NiCr15Fe7TiAl (Germany), NC15FeTNbA (France), NCF750 (Japan)

Material technical standards

Q/3B 4088-1994 "GH4145 Alloy Capillary Material"
 Q/3B 4098-1995 "GH4145 Alloy Wire"
Q/3B 4198-1993 "GH4145 alloy cold rolled plate and strip"

Chemical composition

Surface1-1

Note: Mn and Si in the table are the contents of rods, forgings, ring parts and wires. Plates, strips and pipes are: Mn≤0.35%, Si≤0.35%.

Physical and chemical properties

Thermal performance

It has good corrosion and oxidation resistance below 980℃, high strength below 800℃, good relaxation resistance below 540℃, and good formability and welding performance. The alloy is mainly used to manufacture plane springs and coil springs that work at below 800°C and require high strength and are resistant to relaxation.  [1]

Melting temperature range

1395～1425℃

Thermal conductivity

Table2-1

2.1.3, GH4145 (GH145) linear expansion coefficient see table 2-2

Density

ρ=8.25g/cm3

Electrical properties

Resistivity at 50℃ρ=1.22*10-6Ω.m

Metallographic structure

The structure of the alloy in the standard heat treatment state is composed of γ matrix, Ti (C, N), Nb (C, N), M23C6 carbide and γ'[Ni3(Al, Ti, Nb)] phase, and the γ'content is about 14.5% , Is the main strengthening phase of the alloy.

Process performance requirements

1. The forging temperature of the alloy is easy to form between 1220～950℃. The alloy undergoes solution treatment after the intensive forming process.
2. The average grain size of the alloy is closely related to the degree of deformation of the forging and the final forging temperature.
3. The alloy has good welding performance and can be used for various welding. The aging treatment after welding can obtain the strength close to the fully heat-treated state.
4. The heat treatment of the parts is carried out in a sulfur-free neutral or reducing atmosphere to avoid vulcanization.

Heat treatment system

The solution heat treatment system for the supply of plates, strips and pipes is 980℃±15℃, air cooling. For the intermediate heat treatment system of materials and parts, the following processes can be selected for heat treatment respectively.
 Annealing: 955～1010℃, water cooling.
 Annealing of welded parts before welding: 980℃, 1h.
 Welding parts stress relief annealing: 900℃, moisturizing for 2h.
Stress relief annealing: 885℃±15℃, 24h, air cooling.

Variety specifications and supply status

We can supply various specifications of bars, forgings, ring parts, hot-rolled plates, cold-rolled plates, strips, pipes and wires.
 Plates and strips are generally supplied after hot rolling or cold rolling, annealing or solid solution, pickling and polishing.
 Bars, forgings and ring parts can be supplied in the forged or hot-rolled state; they can also be supplied after forging and solution treatment; the bars can be supplied after solution treatment and polished or turned. When the order requires it, they can be supplied in cold Pull the state in place.
Wire can be supplied in a solid solution state; for wires with a nominal diameter or thickness below 6.35mm, it can be supplied with a cold drawing deformation of 50% to 65% after solid solution; for wires with a nominal diameter or side length greater than 6.35mm Wire materials are supplied with a cold drawing deformation of not less than 30% after solution treatment. For wire with nominal diameter or side length not greater than 0.65mm, it is supplied with a cold drawing deformation of not less than 15% after solution treatment according to requirements.

Melting and casting process

The alloy adopts electric arc furnace plus vacuum consumable remelting, vacuum induction plus electroslag, electroslag plus vacuum consumable remelting or vacuum induction plus vacuum consumable remelting.

Application overview and special requirements

The alloy is mainly used to manufacture corrosion-resistant flat wave springs, circumferential spiral springs, spiral compression springs, spring retainers, seal rings and other parts with aero engine operating temperature below 540°C.